It has become increasingly evident that the known hydrocarbon sources, such as petroleum, are being exhausted at a fairly rapid rate. While no prediction can be made when ultimately petroleum will be exhausted, it has become fairly evident that it will not be in the far future. Consequently, it has become important that other hydrocarbon sources be investigated for ready conversion of these into suitable products.
As one source, shale oil rock has received considerable attention. However, the problems associated with shale oil rock conversion are enormous. These are primarily the inability heretofore to recover the hydrocarbon values from the rock matrix in an economic and industrially acceptable manner. It has been the practice to mine and crush the shale oil rock and then to retort it. Retorting is extremely energy-wasteful. As much as 70% of the energy content of the shale oil rock hydrocarbon values is wasted in the retorting process. A net gain of the shale oil is thus only 30% of the total hydrocarbon values. Retorting also produces a great variety and large amounts of pollutants. Thereafter, the oil must be further processed with a further loss of energy to where the eventual product recovered is so expensive as not to be competitive, at the present time, with any of the known hydrocarbon sources.
With respect to the various methods for recovery of shale oil, a further method for leaving the shale oil in ground and retorting the same in situ has also been suggested. While the energy content recoverable thereby may be improved, the overall net gain is still far below the acceptable proportion so that the processes at the present time appear not to be commercially competitive with other hydrocarbon sources, such as from coal, tar sands, and the like.